1. Field of the Disclosure
Embodiments of the present disclosure generally relate to a magnetic disk device employing a read-write head.
2. Description of the Related Art
To achieve a higher magnetic storage density in a magnetic disk device that employs a read-write head, it is essential to control the physical spacing separating the head from the disk. When the clearance between the read-write head and the disk is too high, the reading/recording performance suffers. As such, the distance between the read-write head of a hard disk drive (HDD) and the disk surface (i.e. the fly height) has been decreasing to the order of nanometers. However, as the spacing between the head and the disk decreases, the potential damage to the HDD increases.
In such a system, every intentional or un-intentional contact between the head and the disk creates wear, especially in the interface materials. Any damage to the interface materials in turn affects the longevity of the HDD. Wear to both the head and disk can occur during a contact situation due to electrochemical processes as the magnetic disk device is reading/writing. Once the drive fails various failure analysis techniques, including atomic force microscope detection (AFM), of the overcoat, can be performed. However, because overcoat wear is critical to the performance of the hard disk drive, there is a need to quantitatively monitor and control the electrochemical wear on the head and disk overcoat before the hard disk drive fails.
Additionally, wear to both the head and disk can occur during a non-contact situation due to electrochemical processes as the magnetic disk device is reading/writing. Thus, real-time monitoring is needed to detect non-contact electrochemical wear during head-disk contact or inadvertent touch downs.
Therefore, an improved method of determining real-time electrochemical head and disk overcoat wear is needed.